/* about.css - 完整解决方案 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    height: 100%;
    background-color: #FFF8F0; /* 根元素背景色 */
}

body {
    min-height: 100%;
    font-family: 'Arial', sans-serif;
    background-color: #FFF8F0; /* 与html一致的双保险 */
    position: relative;
    overflow-x: hidden;
}

/* 顶部固定背景层 - 确保顶部区域被覆盖 */
.top-background-layer {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 120px;
    background-color: #FFF8F0;
    z-index: 90;
    border-bottom: 2px solid #E8D5B5;
}

/* 返回按钮 */
.back-button {
    position: fixed;
    top: 30px;
    left: 30px;
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: #FFF8F0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-decoration: none;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    z-index: 100;
    border: 2px solid #E8D5B5;
}

.back-button span {
    color: #8B4513;
    font-size: 16px;
    line-height: 1.2;
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    position: fixed;
    top: 30px;
    right: 30px;
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: #FFF8F0;
    border: 2px solid #E8D5B5;
    color: #8B4513;
    font-size: 16px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    z-index: 100;
    cursor: pointer;
    outline: none;
}

/* 导航按钮组 */
.nav-buttons {
    position: fixed;
    top: 30px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 20px;
    z-index: 99;
    background-color: rgba(255, 248, 240, 0.95);
    padding: 15px 25px;
    border-radius: 30px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    border: 2px solid #E8D5B5;
}

/* 单个导航按钮 */
.nav-button {
    background-color: #FFF8F0;
    color: #8B4513;
    padding: 12px 25px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: bold;
    font-size: 18px;
    box-shadow: 0 2px 5px rgba(139, 69, 19, 0.1);
    transition: all 0.3s ease;
    border: 2px solid #E8D5B5;
    white-space: nowrap;
}

.nav-button:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 10px rgba(139, 69, 19, 0.2);
}

.nav-button.active {
    background-color: #8B4513;
    color: #FFF8F0;
    border-color: #8B4513;
}

/* 主要内容容器 */
.content-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    padding-top: 120px;
    z-index: 1;
    overflow-y: auto;
    background-color: #FFF8F0;
}

/* 内容iframe */
.content-iframe {
    width: 100%;
    height: 100%;
    border: none;
    background-color: #FFF8F0;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-buttons {
        display: none;
        position: absolute;
        top: 120px;
        left: 0;
        width: 100%;
        flex-direction: column;
        border-radius: 0;
        transform: none;
        padding: 10px;
    }
    
    .nav-buttons.active {
        display: flex;
    }
    
    .mobile-menu-btn {
        display: flex;
        justify-content: center;
        align-items: center;
    }
    
    .content-container {
        padding-top: 100px;
    }
    
    .top-background-layer {
        height: 100px;
    }
    
    .back-button, .mobile-menu-btn {
        width: 60px;
        height: 60px;
        top: 20px;
    }
    
    .back-button {
        left: 20px;
    }
    
    .mobile-menu-btn {
        right: 20px;
    }
}